Many products, including consumer, health care, and professional products, are more effectively used by consumers when containing a feature that can communicate or signal to the user that the product is wetted with an aqueous solution (e.g. urine). One example is a visual wetness indicator that causes the product to change color or appearance when wet. Color indicators can either indicate wetness through a change from colorless to colored or vice versa, or through a change in color saturation.
Exemplary consumer products that could be more effective and deliver more benefits to end users by incorporating a suitable color indicator include absorbent articles such as diapers, feminine pads or incontinence pads and garments. Exemplary professional products that could be more effective and deliver more benefits to end users by incorporating a suitable wetness indicator include products for medical use such as bed pads or bandages. Other products that can benefit from a water-based color indicator include wipes, towels and tissues.
Wetness-indicating inks for such products are well known. Desirable performance attributes include durability and non-leachable. These inks, while wettable, are water insoluble.
To date, water-insoluble indicator inks are volatile organic solvent-based inks that contain water-insoluble dye components (e.g. actives). However, the use of volatile organic solvents not only hinders the manufacture of the absorbent articles noted above due to incompatibility with the manufacturing process of cellulose-based products, such use is also not environmentally friendly and more costly.
While the color-changing compositions known in the art prevent leaching in aqueous environments, there remains a need for a water-based wetness-indicating ink that is environmentally friendly and does not leach. Further sought is an ink that is printable at room temperature and provides a readily discernible color change to the un-aided eye. Desirably, the ink is applicable to various articles including substrates used to make the absorbent articles mentioned herein.